Process for the preparation of alpha-oxoaldehydes

ABSTRACT

Alkylene glycol is oxidized in a vapor phase in the presence of alcohol (a), oxygen, and a catalyst (a) (primary reaction). α-oxoaldehyde, and alcohol (b) or olefin, are oxidized in a vapor phase in the presence of oxygen and a catalyst (b) (secondary reaction). A molar ratio of the alkylene glycol to the alcohol (a) is preferably in a range of 1/100 to 5/1. It is preferable that one same compound is used as the alcohol (a) and the alcohol (b). In the case where the primary and secondary reactions are successively executed, a reaction device in which a primary reactor and a secondary reactor are connected in a two-stage connection type is preferably used. This ensures that a method is provided that is capable of producing α-oxoaldehyde at a higher yield than conventionally, and further, that is capable of stably obtaining an α-oxoaldehyde solution or gas with a higher concentration than conventionally.

This is the U.S. National Stage Application of PCT/JP99/02633 filed May19, 1999.

TECHNICAL FIELD

The present invention relates to a method of production of α-oxoaldehydeby vapor phase reaction, and a method of production of α-oxocarboxylateby vapor phase reaction.

Glyoxal and pyruvic aldehyde (methyl glyoxal) as typical α-oxoaldehydeare chemical compounds very useful in industrial fields, used as variousproducts such as a fiber processing agent, a paper processing agent, asoil hardening agent, or as intermediate materials for various products.Further, glyoxylate as typical α-oxocarboxylate is an industriallyuseful chemical compound: for example, sodium polyacetal carboxylate,which is obtained from polymer of glyoxylate, is used as a builder fordetergents and the like. Further, glyoxylic acid obtained by hydrolysisof glyoxylate is a very useful compound especially for intermediatematerials of various products such as medical products, cosmetics,perfumes, and agricultural chemicals.

BACKGROUND ART

Conventionally, a method of production of α-oxoaldehyde by oxidativedehydrogenation of alkylene glycol in the presence of a silver catalysthas been known. For example, the following methods are known: a methodof obtaining glyoxal at a yield in the 60% order by oxidativedehydrogenation of ethylene glycol, which is the simplest alkyleneglycol, with use of metallic silver (silver crystal) as a catalyst,whose particle diameter is in a range of 0.1 mm to 2.5 mm (the JapaneseExamined Patent Publication 54011/1986 (Tokukosho 61-54011, Date ofPublication: Nov. 20, 1986); and, a method of obtaining glyoxal at ayield of, for example, 82% by oxidative dehydrogenation of ethyleneglycol with use, as a catalyst, of metallic silver modified with aphosphorus-containing compound (the Japanese Publication for Laid-OpenPatent Application No. 38227/1983 [Tokukaisho 58-38227, Date ofPublication: Mar. 5, 1983], the Japanese Publication for Laid-OpenPatent Application No. 59933/1983 [Tokukaisho 58-59933, Date ofPublication: Apr. 9, 1983], the Chinese Patent No. 85100530 [Date ofPublication: Apr. 1, 1985], Catalysis letters, 36(1996) 207-214[received Jul. 10, 1995, Accepted Oct. 11, 1995]). Also known are: amethod of obtaining glyoxal at a yield of 84% by oxidativedehydrogenation of ethylene glycol to which a vaporizedphosphorus-containing compound has been added, with use of a granulatedmetallic silver as a catalyst (the Japanese Publication for Laid-OpenPatent Application No.232835/1991 [Tokukaihei 3-232835, Date ofPublication: Oct. 16, 1991]); and, a method of obtaining glyoxal at ayield in the 70% order by oxidative dehydrogenation of ethylene glycolwith use of, as a catalyst, metallic silver carried by a carrier such assilicon carbide or silicon nitride (The Japanese Examined PatentPublication No.32648/1996 [Tokukohei 8-32648, Date of Publication: Mar.29, 1996]). In these methods, since glyoxal highly tends to bepolymerized, a lot of water (1-3.5 times of ethylene glycol in molarity)is supplied (together with other materials) to a reaction system, sothat glyoxal produced is taken out in, for example, a40-percent-by-weight (wt %) aqueous solution state, as a manufacturedproduct.

The foregoing methods, however, cannot be regarded as methods capable ofproducing glyoxal at a sufficiently high yield and at a highconcentration.

On the other hand, the inventors of the present invention, etc., haveproposed, as a method of producing α-oxocarboxylate from α-oxoaldehyde,a method wherein α-oxoaldehyde and alcohol as materials areoxidative-esterified with use of oxygen and a catalyst (the JapanesePublication for Laid-Open Patent Application No.118650/1997 [Tokukaihei9-118650, Date of Publication: May 6, 1997]). By the foregoing method,by, for example, heating 40 wt % aqueous solution of glyoxal as thesimplest α-oxoaldehyde available in the market, glyoxal in a gaseousstate is obtained as a material. To supply vaporized glyoxal to areaction system, however, sometimes involves difficulties from theviewpoint of industrial application, since the polymerizability ofglyoxal is very high. Besides, it follows that glyoxylate asα-oxocarboxylate is obtained in the presence of water in the reactionsystem, and hence, glyoxylate is sometimes hydrolyzed thereby, possiblyalong with other factors, causing the yield to decrease.

In other words, the foregoing conventional methods have a drawback ofbeing incapable of producing α-oxoaldehyde at a high yield. Further, thesame have a drawback of being incapable of stably obtaining ahigh-concentration α-oxoaldehyde solution or gas. Moreover, because ofthese drawbacks involved in the foregoing methods, there further arisesa problem that it is impossible to produce α-oxocarboxylate at a highyield.

The present invention has been made in light of the foregoingconventional problems, and an object of the present invention is toprovide a method wherein α-oxoaldehyde, at a higher concentration thanconventionally, in a solution state or in a gaseous state, can be stablyproduced at a higher yield than conventionally. Another object of thepresent invention is to provide a method wherein α-oxocarboxylate isproduced at a higher yield than conventionally.

DISCLOSURE OF THE INVENTION

The inventors eagerly studied a method of production of α-oxoaldehydeand a method of production of α-oxocarboxylate, in order to achieve theabove object. As a result, it was found that α-oxoaldehyde could beproduced at a higher yield than conventionally by vapor phase oxidationof alkylene glycol in the presence of alcohol (a), oxygen, and acatalyst, and besides, α-oxoaldehyde solution or gas could be stablyobtained at a higher concentration than conventionally. Further, it wasalso found that α-oxocarboxylate could be produced at a higher yieldthan conventionally by vapor phase oxidation of the α-oxoaldehydeobtained by the foregoing method and, for example, alcohol (b) in thepresence of oxygen and a catalyst. The present invention was completedbased on these findings.

More specifically, to achieve the aforementioned object of the presentinvention, a method of production of α-oxoaldehyde in accordance withthe present invention is characterized in that alkylene glycol isoxidized in a vapor phase in the presence of alcohol (a), oxygen, andcatalyst. Further, the method of production of α-oxoaldehyde inaccordance with the present invention is characterized in that a molarratio of alkylene glycol to alcohol (a) is in a range of 1/100 to 5/1.

To achieve the aforementioned object of the present invention, a methodof production of α-oxocarboxylate in accordance with the presentinvention is characterized by including the steps of oxidizing alkyleneglycol in a vapor phase in the presence of alcohol (a), oxygen, and acatalyst so as to obtain α-oxoaldehyde, and thereafter oxidizing theα-oxoaldehyde, and alcohol (b) or olefin, in a vapor phase in thepresence of oxygen and a catalyst. Further, the method of production ofα-oxocarboxylate in accordance with the present invention ischaracterized in that one and same compound is used as the alcohol (a)and the alcohol (b). Moreover, the method of production ofα-oxocarboxylate in accordance with the present invention ischaracterized in that the alcohol (a) contains unreacted alcohol (b)that is contained in reactant gas resultant from vapor phase oxidationof α-oxoaldehyde and alcohol (b).

For a fuller understanding of the nature and advantages of theinvention, reference should be made to the ensuing detailed descriptiontaken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram schematically illustrating a device for and aprocess of reaction in Example 19.

BEST MODE FOR CARRYING OUT THE INVENTION

A method of production of α-oxoaldehyde in accordance with the presentinvention is a method of vapor phase oxidation of alkylene glycol in thepresence of alcohol (a), oxygen (molecular state), and a catalyst. Amethod of production of α-oxocarboxylate in accordance with the presentinvention is a method of vapor phase oxidation, i.e., oxidativeesterification, of α-oxoaldehyde obtained by the foregoing method, andalcohol (b) or olef in, in the presence of oxygen (molecular state) anda catalyst. Incidentally, in the following descriptions, forconveniences' sake, the reaction wherein α-oxoaldehyde is obtained byvapor phase oxidation of alkylene glycol is referred to as primaryreaction, while the reaction wherein α-oxocarboxylate is obtained byoxidative esterification of α-oxoaldehyde is referred to as secondaryreaction. Further, the catalyst used in the vapor phase oxidation ofalkylene glycol is referred to as catalyst (a), while the catalyst usedin the oxidative esterification of α-oxoaldehyde is referred to ascatalyst (b).

The foregoing alkylene glycol used as material is not specificallylimited, but a compound which vaporizes at a normal pressure(atmospheric pressure) is preferable, and 1,2-diol expressed by theformula (1) below is more preferable:

where R is a hydrogen atom or an organic residue. Concrete examples ofthe 1,2-diol include: ethylene glycol in which a substituent representedby R is a hydrogen atom; 1,2-diol in which a substituent represented byR is a saturated aliphatic hydrocarbon group with 1 to 4 carbon atoms,such as propylene glycol, 1,2-butanediol, 1,2-pentanediol,1,2-hexanediol, 3-methyl-1,2-butanediol, 3-methyl-1,2-pentandiol, or4-methyl-1,2-pentandiol; 1,2-diol in which a substituent represented byR is an unsaturated aliphatic hydrocarbon group with 2 to 3 carbonatoms, such as 1,2-dihydroxy-3-butene, 1,2-dihydroxy-3-pentene, or1,2-dihydroxy-4-pentene; and, 1,2-diol in which a substituentrepresented by R is an aromatic hydrocarbon group, such as1-phenyl-1,2-dihydroxyethane. The 1,2-diol, however, is not particularlylimited. Among the foregoing 1,2-diols, ethylene glycol and propyleneglycol are particularly preferable. In other words, 1,2-diol with 2 to 3carbon atoms are particularly preferable as alkylene glycol.

Concrete examples of alcohol (a) subjected to the primary reaction, thatis, alcohol (a) supplied (together with other materials) to a reactionsystem, include: aliphatic alcohol having 1˜18 carbon atoms that isindustrially available with ease, such as methanol, ethanol, 1-propanol,2-propanol, 1-butanol, 2-butanol, iso-butanol, tert-butanol, hexanol,cyclohexanol, octanol, 2-ethylhexanol, lauryl alcohol, and stearylalcohol. The alcohol (a), however, is not particularly limited. One ofthese may be used, or alternatively, not less than two selectedtherefrom may be used in combination. Among the above-listed examples,aliphatic alcohol having 1 to 4 carbon atoms, such as methanol, ethanol,1-propanol, 2-propanol, 1-butanol, 2-butanol, iso-butanol, ortert-butanol is preferable, and a methanol is more preferable.

A ratio of alcohol (a) to alkylene glycol, i.e., a molar ratio ofalcohol (a) to alkylene glycol, may be set in accordance withcombination of the two, reaction conditions, etc., and is notparticularly limited. It is, however, preferably in a range of 1/100 to5/1, or more preferably in a range of 1/50 to 5/1, or further,particularly preferably in a range of 1/25 to 3/1. By setting the molarratio of the two in the foregoing range, α-oxoaldehyde can be producedat a higher yield. Further, by setting a ratio of alcohol (a) toalkylene glycol lower but in the foregoing range, an α-oxoaldehydesolution or gas with a higher concentration than conventionally can bestably obtained.

Though the catalyst (a) used in the primary reaction is not particularlylimited, examples of the catalyst (a) include metallic catalysts such asmetallic silver, and various oxide catalysts such as CuO—ZnO/α-Al₂O₃,and Ag₂O—SiO₂—ZnO. More concretely, metallic silver (electrolyticsilver), and metallic silver (electrolytic silver) modified with aphosphorus-containing component such as phosphoric acid are preferable.As a form of the catalyst (a), various types including a granulated typeand a reticulate type are applicable, but it is not particularlylimited. A diameter thereof in the case where the catalyst (a) is in agranulated form is, though not particularly limited, preferably in arange of 8 to 60 mesh. Incidentally, the method of preparation of thecatalyst (a) is not particularly limited, but use of metallic silveravailable from the market, which has a predetermined uniform particlediameter, is easy and convenient in the case where a granulated metallicsilver is to be used as the catalyst (a).

The primary reaction is a reaction through which gaseous α-oxoaldehydeis obtained from alkylene glycol, which can be executed in accordancewith any one of various known methods of production of α-oxoaldehyde. Areactor (device) used in the primary reaction may be anything as long asit is capable of vapor phase oxidation, and it is not particularlylimited though a fixed-bed flow-through-type vapor phase reactor, forexample, is preferable. In the case where the fixed-bedflow-through-type vapor phase reactor is used as the reactor whilegranulated metallic silver is used as the catalyst (a), it is preferablethat the catalyst (a) is placed (accumulated) in the fixed-bedflow-through-type vapor phase reactor so that the particle diameterbecomes greater from the gas inlet side to the gas outlet side in thereactor. More specifically, for example, the catalyst (a) placed in thegas inlet side in the reactor preferably has a diameter in a range of 16to 60 mesh, or more preferably in a range of 20 to 30 mesh. On the otherhand, the catalyst (a) placed in the gas outlet side in the reactorpreferably has a diameter in a range of 8 to 30 mesh, or morepreferably, in a range of 10 to 20 mesh. By thus placing (accumulating)the catalyst (a) in a fixed-bed flow-through-type vapor phase reactor,the yield of α-oxoaldehyde can be further improved.

With regard to oxygen subjected to the primary reaction, apart fromoxygen gas, air, or a mixed gas resultant from diluting oxygen gas orair with use of an inactive gas such as nitrogen gas or helium gas maybe applicable. From industrial viewpoint, air or a mixed gas of air andan inactive gas is preferably used as a source of oxygen since it isinexpensive.

A composition of the gas subjected to the primary reaction, that is, agas containing alkylene glycol and alcohol (a) (hereinafter referred toas a supply gas (a)) is not particularly limited, but proportions ofalkylene glycol, oxygen (oxygen gas), and alcohol (a) in the supply gas(a) are preferably, in this order, 1 percent by volume (vol %) to 10 vol%, 1 vol % to 10 vol %, and 0.01 vol % to 30 vol %, respectively (theinactive gas accounts for the rest, and the total is 100 vol %), or morepreferably, 3 vol % to 8 vol %, 3 vol % to 8 vol %, and 0.01 vol % to 20vol %, respectively (the same as the above applies). In the case wherethe composition of the supply gas (a) is out of the above-describedrange, α-oxoaldehyde might not be produced at a yield higher thanconventionally. For example, in the case where the proportion ofalkylene glycol is too high, a side reaction such as combustion tends tooccur, thereby possibly making it impossible to control the primaryreaction.

Further, the supply gas (a) may, as required, contain water (steam). Aproportion of water in the case where the supply gas (a) contains wateris preferably not more than 30 vol %, or more preferably not more than10 vol %. Incidentally, the method of preparation of the supply gas (a)is not particularly limited.

To further improve the yield of α-oxoaldehyde, a phosphorus-containingcompound may be present in the reaction system, or in other words, avaporized phosphorus-containing compound may be added to the supply gas(a) as required. Examples of the phosphorus-containing compound includeorganic phosphorus-containing compounds such as triethyl phosphite, anddiethyl phosphate, but anything may be used as the foregoing compound,provided that it is vaporized under the reaction conditions of theprimary reaction. An amount of the phosphorus-containing compound addedis not particularly limited, but a ratio of the phosphorus to alkyleneglycol is preferably not more than 1 percent by weight (wt %), or morepreferably not less than 40 ppm and not more than 100 ppm. Incidentally,in the case where metallic silver modified with use of aphosphorus-containing compound is used as the catalyst (a), addition ofthe foregoing phosphorus-containing compound in the reaction system isunnecessary.

The reaction conditions of the primary reaction is not particularlylimited, as long as the same may be set depending on a composition ofthe supply gas (a), a type of the catalyst (a), a structure of thereactor, etc., so that the primary reaction can be controlled. Thereaction temperature, however, is preferably set in a range of 400° C.to 700° C., or more preferably in a range of 500° C. to 650° C. Further,a space velocity (SV) is preferably in a range of 5,000 hr⁻¹ to 800,000hr⁻¹, or more preferably in a range of 10,000 hr⁻¹ to 200,000 hr⁻¹. Inthe case where the space velocity is lower than 5,000 hr⁻¹, a sidereaction like combustion may easily occur. In the case where the spacevelocity is higher than 800,000 hr⁻¹, a degree of conversion of alkyleneglycol may possibly decrease.

For example, in the case where metallic silver as the catalyst (a) isplaced in the fixed-bed flow-through-type vapor phase reactor and theprimary reaction under the foregoing reaction conditions with use of thesupply gas (a) containing ethylene glycol as alkylene glycol, preparedso as to have a composition ratio in the foregoing range, is caused totake place, glyoxal as α-oxoaldehyde is obtained at an yield of about80% to 95%, with a degree of conversion of ethylene glycol of about 99%to 100%. Incidentally, the space velocity is an equivalent in the normaltemperature and pressure state (N.T.P.) of a value obtained by dividingan amount (L/hr) of the supply gas (a) supplied per one hour with anamount (L) of the catalyst (a) used in the primary reaction.

As a result of the above-described reaction, a reactant gas containinggaseous α-oxoaldehyde is obtained. A proportion of α-oxoaldehyde in thereactant gas may be set, represented as a concentration of α-oxoaldehydein a solution obtained by condensing the reactant gas, in a range of 45wt % to 80 wt %, or further, 50 wt % to 70 wt %, by appropriatelysetting the reaction conditions of the primary reaction. In other words,α-oxoaldehyde can be produced at a higher yield than conventionally, andan α-oxoaldehyde solution or gas at a higher concentration thanconventionally can be obtained stably. Further, sincehigher-concentration α-oxoaldehyde solution than conventionally can beeasily obtained, costs for transport and storage can be reduced. Amethod for collection and isolation of α-oxoaldehyde are notparticularly limited, and various known methods are applicable. Notα-oxoaldehyde isolated from the reactant gas, but the reactant gascontaining α-oxoaldehyde can be used as it is, in the secondaryreaction.

In the case where 1,2-diol expressed by the aforementioned formula (1)is used as alkylene glycol, α-oxoaldehyde expressed by a formula (2)below is obtained:

where R represents a hydrogen atom or an organic residue. Thoughα-oxoaldehyde is not particularly limited, concrete examples ofα-oxoaldehyde include: glyoxal in that a substituent represented by R isa hydrogen atom; α-oxoaldehyde in that a substituent represented by R isa saturated aliphatic hydrocarbon group with 1 to 4 carbon atoms, suchas pyruvic aldehyde, 2-oxobutanal, 2-oxopentanal, 2-oxohexanal,3-methyl-2-oxobutanal, 3-methyl-2-oxopentanal, or4-methyl-2-oxopentanal; α-oxoaldehyde in that a substituent representedby R is an unsaturated aliphatic hydrocarbon group of 2 to 3 carbonatoms, such as 2-oxo-3-butenal, 2-oxo-4-pentenal, or 2-oxo-3-pentenal;α-oxoaldehyde in that a substituent represented by R is an aromatichydrocarbon group, such as 2-phenyl-2-oxoethanal. According to themethod of the present invention, glyoxal is obtained from ethyleneglycol, while pyruvic aldehyde (methyl glyoxal) is obtained frompropylene glycol.

Incidentally, the reactant gas containing α-oxoaldehyde containsformaldehyde, carbon monoxide, carbon dioxide, water, etc. asby-products that are produced by side reaction like combustion. Though apart of alcohol (a) added is lost by side reaction such as combustion,about 90 wt % of the same is recovered, while about 10 wt % is convertedto formaldehyde.

The detailed reason why the presence of alcohol (a) stabilizesα-oxoaldehyde in the primary reaction, that is, enables production ofα-oxoaldehyde at a higher yield than in the conventional cases isunknown, but it is presumed that it is because α-oxoaldehyde, along withalcohol (a), forms hemiacetal.

Concrete examples of the aforementioned alcohol (b) subjected to thesecondary reaction include alcohols applicable as the foregoing alcohol(a), and aromatic alcohols such as phenol and benzyl alcohol, though thealcohol (b) is not particularly limited. One of these may be used, oralternatively, not less than two selected therefrom may be used incombination. Among the above-listed examples, aliphatic alcohol having 1to 4 carbon atoms, such as methanol, ethanol, 1-propanol, 2-propanol,1-butanol, 2-butanol, iso-butanol, or tert-butanol is preferable, andmethanol is more preferable.

Then, to enable the foregoing alcohol (a) to be applied as the alcohol(b), it is most preferable that one and same chemical compound is usedas the alcohols (a) and (b). In other words, alcohol to be used as thealcohol (b) in the secondary reaction is preferably used as the alcohol(a) in the primary reaction. In this case, alcohol (a) need not beremoved from α-oxoaldehyde prior to the secondary reaction. Furthermore,alcohol that is contained in a reactant gas resultant from the secondaryreaction, remaining therein uncollected upon collection (separation) ofα-oxocarboxylate and other produced matters from the reactant gas, canbe applied, as it is, as alcohol (a) for the primary reaction. Thismakes the production of α-oxocarboxylate further easier.

Concrete examples of the aforementioned olefin subjected to thesecondary reaction include those having 2 to 4 carbon atoms, such asethylene, propylene, 1-butene, 2-butene, and isobutene, though olefin isnot particularly limited. One of these olefins may be used, oralternatively, not less than two selected therefrom may be used incombination as required.

A ratio of alcohol (b) or olefin (hereinafter simply referred to asalcohol (b)) to α-oxoaldehyde, that is, a molar ratio of alcohol (b) toα-oxoaldehyde, may be preferably equivalent (1/1) in stoichiometry, butit may be set depending on combination of the two, reaction conditions,etc., and is not particularly limited.

Examples of the catalyst (b) used in the secondary reaction includemetallic catalysts such as metallic silver, and other various catalystsbased on oxides. Among these examples, a catalyst containing aphosphorus-containing inorganic oxide is preferable. Thephosphorus-containing inorganic oxide is not particularly limited, asvarious chemical compounds are applicable as the same, but metallicphosphate and phosphorus-containing heteropolyacid are preferable. Notethat a mixture of metallic phosphate and phosphorus-containingheteropolyacid can be used as catalyst (b).

The kinds of metal of metallic phosphate are not limited as long asphosphate can be produced. Examples of such metal include: alkali metal,alkaline earth metal, B, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Zr, Mo, Pd,Ag, Cd, Sn, Pb, etc. One kind of metal selected therefrom may becontained in metallic phosphate, or alternatively, not less than twoselected therefrom may be contained in metallic phosphate. In otherwords, metallic phosphate may contain not less than two kinds of metal.Further, not less than two kinds of metallic phosphate may be used incombination. In other words, examples of metallic phosphate as catalyst(b) include: metallic phosphate containing one type of metal; metallicphosphate containing not less than two types of metal; and a mixture ofnot less than two kinds of such metallic phosphate. Further, it ispossible to place different kinds of metallic phosphate as catalyst (b),respectively on the gas inlet side and the gas outlet side in thereactor used in the secondary reaction.

A molar ratio of the metal to phosphorus in metallic phosphate does notnecessarily agree with stoichiometric mixture ratio of orthophosphate,but is preferably approximate to the stoichiometric mixture ratio, andmore specifically, preferably in a range of 1/0.5 to 1/2.

A method of preparation of metallic phosphate is not particularlylimited, and examples of the same include various known methods such as:a coprecipitation method wherein metallic phosphate is coprecipitated inan aqueous solution obtained by mixing and dissolving a metallic saltand a phosphorus source; and a kneading method wherein a metallic saltand a phosphorus source are mixed and formed in a slurry form, andthereafter, kneaded so that metallic phosphate is obtained.Alternatively, as the foregoing metallic phosphate, a reagent availablefrom the market can be used. Examples of the metallic salt includenitrate, carbonate, oxalate, hydroxide, and chloride, though themetallic salt is not particularly limited. Any one selected therefrommay be used, or alternatively, not less than two selected therefrom maybe used in combination. Examples of the phosphorus source includephosphate such as orthophosphate, ammonium phosphate, diammoniumhydrogenphosphate, or ammonium dihydrogenphosphate, though thephosphorus source is not particularly limited. Any one phosphorus sourceselected therefrom may be used, or alternatively, not less than twoselected therefrom may be used in combination. A combination of themetallic salt and the phosphorus source is not particularly limited, andvarious combinations thereof are applicable.

Though depending on a kind and composition of metallic phosphate, themetallic phosphate is preferably dried in air at a temperature in arange of 100° C. to 120° C., calcined in air at a temperature in a rangeof 300° C. to 1000° C., or more preferably in a range of 400° C. to 800°C., and further, preferably subjected to a pre-processing operation suchas molding or granulating to make the particle diameter uniform,according to necessity. Incidentally, metallic phosphate can be used ascatalyst (b) without pre-processing.

Furthermore, the metallic phosphate in combination with an inorganicoxide, in a state of a mixture of the same, is preferably used as thecatalyst (b). Examples of inorganic oxide include silica, titania,zirconia, niobium oxide, and diatomaceous earth, but the inorganic oxideis not particularly limited. For the titania, both anatase type andrutile type may be used. Any one inorganic oxide selected therefrom maybe used, or alternatively, not less than two selected therefrom may beused in combination. An amount of inorganic oxide to be mixed in themetallic phosphate varies depending on the kind and composition ofmetallic phosphate, and the kind of the inorganic oxide. However, aproportion of the inorganic oxide in the total amount of metallicphosphate and the inorganic oxide is preferably in a range of 1 wt % to90 wt %, more preferably, 10 wt % to 60 wt %. Note that metallicphosphate as it is can be used as catalyst (b), without being mixed withan inorganic oxide as described above.

The phosphorus-containing heteropolyacid is not particularly limited.However, Keggin type heteropolyacid expressed by the following formulais preferable because of its excellent function as a catalyst:

H_(a)PM₁₂O₄₀.nH₂O

wherein M is a metal element of at least one selected from the groupconsisting of tungsten, molybdenum and vanadium, a is a numerical valuedetermined by M, and n is 0 or a positive integer.

Further, the Keggin-type heteropolyacid in that a part or all of H issubstituted with metal such as alkali metal, alkaline earth metal, andtransition metal, that is, heteropolyacid salt expressed by thefollowing formula, can be used:

H_((a-b))M′_(b)PM₁₂O₄₀.nH₂O

wherein M is a metal element of at least one selected from the groupconsisting of tungsten, molybdenum and vanadium, M′ is a metal elementsuch as an alkali metal, alkaline earth metal, transition metal, etc., ais a numerical value determined by M, b is a numerical value selected atrandom from the range of 0<b≦a, and n is 0 or a positive integer. Amethod of preparation of Keggin type heteropolyacid or heteropolyacidsalt, that is, a method of preparation of the foregoingphosphorus-containing heteropolyacid, is not particularly limited, andany one of various known methods is applicable.

Though depending on a type and composition of the phosphorus-containingheteropolyacid, the phosphorus-containing heteropolyacid is preferablydried in air and thereafter calcined in air prior to the secondaryreaction at higher temperature than the reaction temperature of thesecondary reaction. Note that, however, the phosphorus-containingheteropolyacid may be used as catalyst (b) without applying thereto theforegoing treatment.

Further, it is preferable to use as catalyst (b) thephosphorus-containing heteropolyacid in a state of being carried on acarrier. Concrete examples of such a carrier include silica, titania,zirconia, niobium oxide, and diatomaceous earth, but anything isapplicable as the carrier, provided that it does not have adverseeffects on the secondary reaction and is stable againstphosphorus-containing heteropolyacid. For the titania, both the anatasetype and the rutile type are applicable. Any one carrier may be usedalone, or alternatively, not less than two carriers may be used incombination. The method of making the carrier carryphosphorus-containing heteropolyacid is not particularly limited, and aso-called kneading method, or the impregnating supporting method may beadopted. Note that phosphorus-containing heteropolyacid can be adoptedalone so as to be used as catalyst (b), without being carried on acarrier.

The secondary reaction is a reaction through which gaseousα-oxocarboxylate is obtained from α-oxoaldehyde, which can be executedin accordance with any one of various known reactions of oxidation andoxidative esterification. A reactor (device) used in the secondaryreaction is not particularly limited as long as it is capable ofoxidative esterification, though a fixed-bed flow-through-type vaporphase reactor, for example, is preferable.

With regard to oxygen used in the secondary reaction, apart from oxygengas, air, or a mixed gas obtained by diluting oxygen gas or air with useof an inactive gas such as nitrogen gas or helium gas, may beapplicable. From industrial viewpoint, air or a mixed gas of air and aninactive gas is preferably used as a source of oxygen since it isinexpensive.

A composition of the gas subjected to the secondary reaction, that is, agas containing α-oxoaldehyde and alcohol (b) (hereinafter referred to asa supply gas (b)) is not particularly limited, but proportions ofα-oxoaldehyde, oxygen (oxygen gas), and alcohol (b) in the supply gas(b) are preferably, in this order, 1 to 10 vol %, 1 to 10 vol %, and 5to 50 vol % (the inactive gas accounts for the rest, and the total is100 vol %). In the case where the composition of the supply gas (b) isout of the above-described range, α-oxocarboxylate might not be producedat a yield higher than conventionally, and an amount of recoveredalcohol (b) might increase. Further, the supply gas (b) may, asrequired, contain water (steam) produced (as by-product) in the primaryreaction. Incidentally, a method of preparation of the supply gas (b) isnot particularly limited.

The reaction conditions of the secondary reaction are not particularlylimited as long as the same may be set depending on the composition ofthe supply gas (b), the type of the catalyst (b), the structure of thereactor, etc., so that the secondary reaction can be controlled. Thereaction temperature, however, is preferably set in a range of 150° C.to 500° C., or more preferably in a range of 180° C. to 400° C. Further,a space velocity (SV) is preferably in a range of 100 hr⁻¹ to 10,000hr⁻¹, or more preferably in a range of 500 hr⁻¹ to 5,000 hr⁻¹.Incidentally, the space velocity is an equivalent in the normaltemperature and pressure state (N.T.P.) of a value obtained by dividingan amount (L/hr) of the supply gas (b) supplied per one hour with anamount (L) of the catalyst (b) used in the secondary reaction.

By executing the above-described reaction, a reactant gas containinggaseous α-oxocarboxylate is obtained. More specifically, inconveniencesinvolved in the conventional methods, for example, hydrolysis ofα-oxocarboxylate due to the presence of water in the reaction system,can be avoided, thereby ensuring that α-oxocarboxylate can be producedat a higher yield than conventionally. A method for collection andisolation of gaseous α-oxocarboxylate are not particularly limited, andvarious known methods are applicable. By the method of the presentinvention, glyoxylate can be obtained from glyoxal, while pyruvate isobtained from pyruvic aldehyde.

Incidentally, the reactant gas containing, apart from unreacted oxygengas and alcohol (b), α-oxocarboxylate contains formaldehyde, carbonmonoxide, carbon dioxide, water, etc. as by-products that are producedby side reaction like combustion.

In the production of α-oxocarboxylate in accordance with the presentinvention, a reactant gas containing α-oxoaldehyde, resultant from theprimary reaction, can be used as it is, as a material for the secondaryreaction. In other words, in the production of α-oxocarboxylate inaccordance with the present invention, the primary reaction and thesecondary reaction can be executed successively. In this case, forexample, a fixed-bed flow-through-type vapor phase reactor wherein areactor used for the primary reaction and a reactor used for thesecondary reaction are connected, that is, a so-called two-stageconnection type, is preferable, though the reactor is not particularlylimited. In the case where the fixed-bed flow-through-type vapor phasereactor, for example, is used, a reactant gas containing α-oxoaldehydeis obtained by flowing the supply gas (a) through the reactor at thefirst stage provided with the catalyst (a), and thereafter, the supplygas (b) is prepared by adding alcohol (b), oxygen, etc. to the reactantgas obtained and is flown through the reactor at the second stageprovided with the catalyst (b), whereby a reactant gas containingα-oxocarboxylate is obtained.

Thus, by successively executing the primary reaction and the secondaryreaction, or to state differently, by combining different vapor phasereactions in succession, α-oxocarboxylate can be produced from alkyleneglycol through a substantially single stage without taking gaseousα-oxoaldehyde out of the reaction system.

In the case where the primary and secondary reactions are successivelyexecuted, the reactant gas resultant from the secondary reaction, gasresulting on separation of α-oxocarboxylate and other produced mattersfrom the foregoing reactant gas, and gas containing alcohol uncollectedupon separation and collection of alcohol from the foregoing gas can bere-used (recycled) as at least a part, or more preferably an entirety,of the supply gas (a) for the primary reaction. Produced mattersincluding α-oxocarboxylate can be easily collected by condensing thereactant gas resultant from the secondary reaction with use of acondenser or the like. In this case, alcohol (a) used in the primaryreaction contains unreacted alcohol (b) contained in the reactant gasresultant from the secondary reaction. Therefore, in the case where thesame chemical compound is used as alcohol (a) and alcohol (b) and theforegoing recycling is carried out, production of α-oxocarboxylate fromalkylene glycol is made further simpler and more efficient. Morespecifically, since complete separation of unreacted alcohol (b) isunnecessary upon re-use of a part or an entirety of the supply gas (a)for the primary reaction, costs for the separation can be cut.

As described above, a method of production of α-oxoaldehyde inaccordance with the present invention is a method wherein alkyleneglycol is oxidized in a vapor phase in the presence of alcohol (a),oxygen, and catalyst (a). By the foregoing method, the presence ofalcohol (a) stabilizes α-oxoaldehyde, thereby resulting in that supplyof, for example, water to obtain α-oxoaldehyde is unnecessary.Therefore, by the foregoing method, α-oxoaldehyde can be produced at ahigher yield than conventionally, and further, an α-oxoaldehyde solutionor gas at a higher concentration than conventionally can be stablyobtained.

As described above, the method of production of α-oxocarboxylate inaccordance with the present invention is a method wherein α-oxoaldehydeobtained by the above-described method, and alcohol (b) or olefin areoxidized in a vapor phase in the presence of oxygen and catalyst (b). Bythe foregoing method, inconveniences involved in the conventionalmethods can be avoided. More specifically, a 40 wt % aqueous solution ofglyoxal available in the market need not be used as a material for thesecondary reaction, and massive water need not be supplied to a reactionsystem when α-oxoaldehyde is obtained from the primary reaction, either,thereby ensuring that hydrolysis of α-oxocarboxylate in the secondaryreaction can be avoided. Therefore, α-oxocarboxylate can be produced ata higher yield than conventionally.

The method of production of α-oxocarboxylate in accordance with thepresent invention is a method wherein, as the foregoing alcohol (a), agas containing unreacted alcohol (b) that is contained in a reactant gasobtained by vapor phase oxidation of α-oxoaldehyde and the alcohol (b)is used. By the foregoing method, for example, a reactant gas resultantfrom the secondary reaction, a gas resulting on separation of producedmatters from the reactant gas, or a gas containing alcohol (b) notcollected upon separation and collection of alcohol (b) from theforegoing gas, is re-used as a part, or preferably an entirety, of thesupply gas (a) for the primary reaction. In this case, since the alcohol(a) re-used contains unreacted alcohol (b), production ofα-oxocarboxylate from alkylene glycol is made simpler and more efficientin the case where one and same chemical compound is used as the alcohol(a) and the alcohol (b) and the re-use as described is executed.

The present invention will be described more specifically below withreference to examples and comparative examples. It should be noted thatthe scope of the present invention is not limited to these examples. Inthe following examples and comparative examples, executed were areaction (primary reaction) in which glyoxal (hereinafter referred to asGLO) as α-oxoaldehyde is obtained from ethylene glycol (hereinafterreferred to as EG) as alkylene glycol, and in succession from theprimary reaction, a reaction (secondary reaction) in which methylglyoxylate (hereinafter referred to as MGO) as α-oxocarboxylate isobtained from GLO.

A reactant gas resultant from the primary reaction, cooled to a freezingpoint, was collected with water, and was analyzed, using a high speedliquid chromatography equipped with a differential refractometerdetector under predetermined conditions, adopting the internal standardmethod. In other words, unreacted EG contained in the foregoing reactantgas and GLO produced were quantified.

Further, the reactant gas resultant from the secondary reaction, cooledto a freezing point, was collected with acetonitrile, and was analyzed,using a high speed liquid chromatography equipped with a differentialrefractometer detector and a gaschromatography equipped with an FID(flame ionization detector) under predetermined conditions, adopting theinternal standard method. In other words, unreacted GLO contained in theforegoing reactant gas was quantified using the high speed liquidchromatography, while produced MGO contained in the reactant gas wasquantified using the gaschromatography.

Conversion, yield, and selectivity shown in the descriptions of theexamples and comparative examples were calculated, using results of theforegoing quantification, according to the following formulas:

The reacted EG (mol)=EG supplied (mol)−unreacted EG (mol)

The conversion of EG (%)=(reacted EG (mol)/EG supplied (mol))×100

$\begin{matrix}{{\text{The yield of}\text{GLO}\text{(\%)}} = \quad {{\text{(}\text{GLO}\text{produced from the primary reaction (mol)}}/}} \\{\left. \quad {{EG}\quad {supplied}\quad ({mol})} \right) \times 100}\end{matrix}$

 The reacted GLO (mol)=GLO supplied (mol)−unreacted GLO (mol)

The conversion of GLO (%)=(reacted GLO (mol)/GLO supplied (mol))×100

The selectivity of MGO (%)=(MGO produced (mol)/reacted GLO (mol))×100

The yield of MGO with respect to EG (%)=(MGO produced (mol)/EG supplied(mol))×100

EXAMPLE 1

GLO was obtained from EG through the primary reaction. An SUS (StainlessSteel) pipe with an inner diameter of 12 mm was used as a reaction pipe(primary reactor), in which placed (laminated) was 15 g of metallicsilver (electrolytic silver with a particle diameter of 20 to 30 mesh,available from Yokohama Metal Co., Ltd.) as catalyst (a). Further, on agas inlet side of the reaction pipe, a vaporizer was attached so as toheat to a predetermined temperature a supply gas (a) to be supplied tothe reaction pipe. Further, the reaction pipe has a heat insulatingmaterial wound therearound for heat retention, so that the temperatureof a catalyst layer during the primary reaction (reaction temperature)would be kept at a predetermined temperature. In other words, heatretention was ensured so that the primary reaction proceeded underconditions substantially equivalent to those of adiabatic reaction.

Proportions of EG, oxygen, methanol as alcohol (a), and water in thesupply gas (a) were set, in this order, 4.0 vol %, 4.8 vol %, 3.0 vol %,and 0 vol %, respectively (nitrogen gas accounted for the rest, and thetotal was 100 vol %: this is hereinafter referred to as nitrogen gasbalance). To the foregoing supply gas (a), triethyl phosphite as aphosphorus-containing compound was added so that a ratio of phosphorusto EG became 60 ppm.

The supply gas (a) of the foregoing composition was continuouslysupplied to the reaction pipe at a space velocity (SV) of 45,000 hr⁻¹,so that the primary reaction occurred. The reaction temperature, thatis, the temperature of the catalyst layer, reached 570° C. Main reactionconditions are shown in Table 1.

A composition of a reactant gas obtained was analyzed in theaforementioned manner. Consequently, the conversion of EG was 100%, andthe yield of GLO was 88%. The result is shown in Table 3.

EXAMPLE 2

The primary reaction was made to take place under the same conditions asin Example 1 except that the proportions of EG, oxygen, methanol, andwater in the supply gas (a) were changed to, in this order, 4.0 vol %,4.8 vol %, 4.0 vol %, and 0 vol %, respectively (nitrogen gas balance).The temperature of the catalyst layer reached 565° C. Main reactionconditions are shown in Table 1. Consequently, the conversion of EG was100%, and the yield of GLO was 89%. The result is shown in Table 3.Incidentally, a very small amount of glycol aldehyde produced as areaction intermediate (by-product) was detected. An amount of methanollost by side reaction such as combustion was 10 wt % of an amountsupplied.

Comparative Example 1

A comparison-use supply gas (a) containing no alcohol (a) was used inthe primary reaction. In other words, the primary reaction was made totake place under the same conditions as in Example 1 except that theproportions of EG, oxygen, methanol, and water in the comparison-usesupply gas (a) were set to, in this order, 4.0 vol %, 4.8 vol %, 0 vol%, and 0 vol %, respectively (nitrogen gas balance). The temperature ofthe catalyst layer reached 586° C. Main reaction conditions are shown inTable 1. Consequently, the conversion of EG was 100%, but the yield ofGLO was as low as 77%. The result is shown in Table 3.

Comparative Example 2

A comparison-use supply gas (a) containing water instead of alcohol (a)was used in the primary reaction. In other words, the primary reactionwas made to take place under the same conditions as in Example 1 exceptthat the proportions of EG, oxygen, methanol, and water in thecomparison-use supply gas (a) were set to, in this order, 4.0 vol %, 4.8vol %, 0 vol %, and 3.0 vol %, respectively (nitrogen gas balance). Thetemperature of the catalyst layer reached 583° C. Main reactionconditions are shown in Table 1. Consequently, the conversion of EG was100%, but the yield of GLO was as low as 79%. The result is shown inTable 3.

EXAMPLE 3

The primary reaction was made to take place under the same conditions asin Example 1 except that the proportions of EG, oxygen, methanol, andwater in the supply gas (a) were set to, in this order, 4.0 vol %, 4.8vol %, 20.0 vol %, and 3.0 vol %, respectively (nitrogen gas balance),and that triethyl phosphite was added to the supply gas (a) so that aratio of phosphorus to EG became 80 ppm. The temperature of the catalystlayer reached 569° C. Main reaction conditions are shown in Table 1.Consequently, the conversion of EG was 100%, and the yield of GLO was89%. The result is shown in Table 3.

EXAMPLE 4

The primary reaction was made to take place under the same conditions asin Example 1 except that the proportions of EG, oxygen, methanol, andwater in the supply gas (a) were changed to, in this order, 4.0 vol %,4.8 vol %, 3.0 vol %, and 1.0 vol %, respectively (nitrogen gasbalance). The temperature of the catalyst layer reached 567° C. Mainreaction conditions are shown in Table 1. Consequently, the conversionof EG was 100%, and the yield of GLO was 89%. The result is shown inTable 3.

EXAMPLE 5

The primary reaction was made to take place under the same conditions asin Example 1 except that the proportions of EG, oxygen, methanol, andwater in the supply gas (a) were changed to, in this order, 4.0 vol %,4.8 vol %, 1.0 vol %, and 0 vol %, respectively (nitrogen gas balance).The temperature of the catalyst layer reached 583° C. Main reactionconditions are shown in Table 1. Consequently, the conversion of EG was100%, and the yield of GLO was 82%. The result is shown in Table 3. AGLO aqueous solution obtained had a concentration of about 58 wt %,which is higher than the concentration of a GLO aqueous solutionavailable from the market (40 wt %). In other words, a GLO aqueoussolution with a higher concentration than that available from the marketcould be obtained stably.

EXAMPLE 6

The primary reaction was made to take place under the same conditions asin Example 1 except that the proportions of EG, oxygen, methanol, andwater in the supply gas (a) were changed to, in this order, 4.0 vol %,4.0 vol %, 4.0 vol %, and 0 vol %, respectively (nitrogen gas balance).The temperature of the catalyst layer reached 573° C. Main reactionconditions are shown in Table 1. Consequently, the conversion of EG was99%, and the yield of GLO was 85%. The result is shown in Table 3.

EXAMPLE 7

The primary reaction was made to take place under the same conditions asin Example 1 except that the proportions of EG, oxygen, methanol, andwater in the supply gas (a) were changed to, in this order, 4.0 vol %,6.0 vol %, 4.0 vol %, and 0 vol %, respectively (nitrogen gas balance).The temperature of the catalyst layer reached 572° C. Main reactionconditions are shown in Table 1. Consequently, the conversion of EG was100%, and the yield of GLO was 89%. The result is shown in Table 3.

EXAMPLE 8

The primary reaction was made to take place under the same conditions asin Example 1 except that the proportions of EG, oxygen, methanol, andwater in the supply gas (a) were changed to, in this order, 3.0 vol %,4.0 vol %, 3.0 vol %, and 0 vol %, respectively (nitrogen gas balance).The temperature of the catalyst layer reached 557° C. Main reactionconditions are shown in Table 2. Consequently, the conversion of EG was99%, and the yield of GLO was 86%. The result is shown in Table 3.

EXAMPLE 9

The primary reaction was made to take place under the same conditions asin Example 1 except that the proportions of EG, oxygen, methanol, andwater in the supply gas (a) were changed to, in this order, 5.0 vol %,6.0 vol %, 4.0 vol %, and 0 vol %, respectively (nitrogen gas balance).The temperature of the catalyst layer reached 588° C. Main reactionconditions are shown in Table 2. Consequently, the conversion of EG was100%, and the yield of GLO was 84%. The result is shown in Table 3.

EXAMPLE 10

The primary reaction was made to take place under the same conditions asin Example 1 except that the proportions of EG, oxygen, methanol, andwater in the supply gas (a) were changed to, in this order, 5.0 vol %,6.0 vol %, 4.0 vol %, and 1.0 vol %, respectively (nitrogen gasbalance). The temperature of the catalyst layer reached 587° C. Mainreaction conditions are shown in Table 2. Consequently, the conversionof EG was 100%, and the yield of GLO was 84%. The result is shown inTable 3.

EXAMPLE 11

GLO was obtained from EG through the primary reaction in an identicalmanner to that in Example 1, except that 10 g of metallic silver(electrolytic silver available from Yokohama Metal Co., Ltd.) with aparticle diameter of 20 to 30 mesh was placed (laminated) on the gasinlet side in the reaction pipe, while log of metallic silver (the sameas above) with a particle diameter of 16 to 20 mesh was placed(laminated) on the gas outlet side in the reaction pipe.

The primary reaction was made to take place under the same conditions asin Example 1 except that the proportions of EG, oxygen, methanol, andwater in the supply gas (a) were changed to, in this order, 4.0 vol %,4.8 vol %, 4.0 vol %, and 0 vol %, respectively (nitrogen gas balance).The temperature of the catalyst layer reached 555° C. Main reactionconditions are shown in Table 2. Consequently, the conversion of EG was100%, and the yield of GLO was 91%. The result is shown in Table 3. AGLO aqueous solution obtained had a concentration of about 56 wt %,which is higher than the concentration of a GLO aqueous solutionavailable from the market (40 wt %). In other words, a GLO aqueoussolution with a higher concentration than that available from the marketcould be obtained stably.

EXAMPLE 12

The primary reaction was made to take place under the same conditions asin Example 11 except that the supply gas (a) was continuously suppliedto the reaction pipe so that the space velocity (SV) became 100,000hr⁻¹. The temperature of the catalyst layer reached 554° C. Mainreaction conditions are shown in Table 2. Consequently, the conversionof EG was 100% and the yield of GLO was 90%. The result is shown inTable 3.

EXAMPLE 13

The primary reaction was made to take place under the same conditions asin Example 11 except that an amount of metallic silver placed on the gasoutlet side in the reaction pipe was set to 5 g and that the supply gas(a) was continuously supplied to the reaction pipe so that the spacevelocity (SV) became 70,000 hr⁻¹. The temperature of the catalyst layerreached 555° C. Main reaction conditions are shown in Table 2.Consequently, the conversion of EG was 99%, and the yield of GLO was90%. The result is shown in Table 3. Incidentally, a very small amountof glycol aldehyde produced as a reaction intermediate (by-product) wasdetected. An amount of methanol lost by side reaction such as combustionwas 13 wt % of an amount supplied.

EXAMPLE 14

The primary reaction was made to take place under the same conditions asin Example 11 except that an amount of metallic silver placed on the gasoutlet side in the reaction pipe was set to 5 g, that the proportions ofEG, oxygen, methanol, and water in the supply gas (a) were changed to,in this order, 4.0 vol %, 4.8 vol %, 20.0 vol %, and 0 vol %,respectively (nitrogen gas balance), and that triethyl phosphite wasadded to the supply gas (a) so that a ratio of phosphorus to EG became100 ppm. The temperature of the catalyst layer reached 558° C. Mainreaction conditions are shown in Table 2. Consequently, the conversionof EG was 100%, and the yield of GLO was 91%. The result is shown inTable 3.

EXAMPLE 15

Metallic silver modified with use of phosphorus-containing compound ascatalyst (a) was prepared in the following manner. More specifically, 85wt % aqueous solution of phosphoric acid was added to metallic silver(electrolytic silver available from Yokohama Metal Co., Ltd.) with aparticle diameter of 20 to 30 mesh so that a ratio of phosphorus tosilver became 200 ppm. Thus, metallic silver was made to carryphosphorus. The metallic silver carrying phosphorus was dried in air at120° C., and thereafter, calcined in air at 600° C. for 3 hours. In thisway, metallic silver modified with use of phosphoric acid(phosphorus-containing compound) was prepared, as catalyst (a).

Using the foregoing metallic silver as catalyst (a), GLO was obtainedfrom EG through the primary reaction performed in an identical manner tothat in Example 1. More specifically, the primary reaction was made totake place under the same conditions as in Example 1 except that theproportions of EG, oxygen, methanol, and water in the supply gas (a)were changed to, in this order, 4.0 vol %, 4.8 vol %, 4.0 vol %, and 1.0vol %, respectively (nitrogen gas balance), that an amount of metallicsilver placed in the reaction pipe was set to 5 g, and that aphosphorus-containing compound was not supplied along with the supplygas (a). The temperature of the catalyst layer reached 590° C. Mainreaction conditions are shown in Table 2. Consequently, the conversionof EG was 100%, and the yield of GLO was 79%. The result is shown inTable 3.

EXAMPLE 16

Metallic silver modified with use of phosphoric acid was preparedthrough the same operation as that in Example 15 except that 85 wt %aqueous solution of phosphoric acid was added to metallic silver so thata ratio of phosphorus to silver became 80 ppm.

Using as catalyst (a) the metallic silver thus obtained, GLO wasobtained from EG through the primary reaction performed in an identicalmanner to that in Example 1. More specifically, the primary reaction wasmade to take place under the same conditions as in Example 1 except thatan amount of metallic silver placed in the reaction pipe was set to 5 g,that the proportions of EG, oxygen, methanol, and water in the supplygas (a) were changed to, in this order, 4.0 vol %, 4.8 vol %, 4.0 vol %,and 1.0 vol %, respectively (nitrogen gas balance). The temperature ofthe catalyst layer reached 578° C. Main reaction conditions are shown inTable 2. Consequently, the conversion of EG was 100%, and the yield ofGLO was 82%. The result is shown in Table 3.

TABLE 1 COMPOSITION OF SUPPLY GAS (a) AMOUNT OF SPACE CATALYST (a) (vol%, NITROGEN SUPPLIED VELOCITY PARTICLE TEMPERATURE OF GAS BALANCE)PHOSPHORUS SV DIAMETER AMOUNT CATALYST LAYER EG O₂ MeOH H₂O (ppm) (hr⁻¹)(mesh) (g) (° C.) EX. 1 4.0 4.8 3.0 0 60 45000 20-30 15 570 EX. 2 4.04.8 4.0 0 60 45000 20-30 15 565 COMP. EX. 1 4.0 4.8 0 0 60 45000 20-3015 586 COMP. EX. 2 4.0 4.8 0 3.0 60 45000 20-30 15 583 EX. 3 4.0 4.820.0 3.0 80 45000 20-30 15 569 EX. 4 4.0 4.8 3.0 1.0 60 45000 20-30 15567 EX. 5 4.0 4.8 1.0 0 60 45000 20-30 15 583 EX. 6 4.0 4.0 4.0 0 6045000 20-30 15 573 EX. 7 4.0 6.0 4.0 0 60 45000 20-30 15 572

TABLE 2 COMPOSITION OF SUPPLY GAS (a) AMOUNT OF SPACE CATALYST (a) (vol%, NITROGEN SUPPLIED VELOCITY PARTICLE TEMPERATURE OF GAS BALANCE)PHOSPHORUS SV DIAMETER AMOUNT CATALYST LAYER EG O₂ MeOH H₂O (ppm) (hr⁻¹)(mesh) (g) (° C.) EX. 8 3.0 4.0 3.0 0 60 45000 20-30 15 557 EX. 9 5.06.0 4.0 0 60 45000 20-30 15 588 EX. 10 5.0 6.0 4.0 1.0 60 45000 20-30 15587 EX. 11 4.0 4.8 4.0 0 60 45000 20-30 10 555 16-20 10 EX. 12 4.0 4.84.0 0 60 100000  20-30 10 554 16-20 EX. 13 4.0 4.8 4.0 0 60 70000 20-3010 555 16-20 EX. 14 4.0 4.8 20.0 0 100 45000 20-30 10 558 16-20 EX. 154.0 4.8 4.0 1.0 0 45000 20-30 5 590 EX. 16 4.0 4.8 4.0 1.0 60 4500020-30 5 578

TABLE 3 CONVERSION OF EG YIELD OF GLO (%) (%) EXAMPLE 1 100 88 EXAMPLE 2100 89 COMPARATIVE EX. 1 100 77 COMPARATIVE EX. 2 100 79 EXAMPLE 3 10089 EXAMPLE 4 100 89 EXAMPLE 5 100 82 EXAMPLE 6  99 85 EXAMPLE 7 100 89EXAMPLE 8  99 86 EXAMPLE 9 100 84 EXAMPLE 10 100 84 EXAMPLE 11 100 91EXAMPLE 12 100 90 EXAMPLE 13  99 90 EXAMPLE 14 100 91 EXAMPLE 15 100 79EXAMPLE 16 100 82

EXAMPLE 17

MGO was obtained from GLO through the secondary reaction. Titania-addediron phosphate as catalyst (b) was prepared in the following manner.

Namely, iron phosphate (FePO₄.4H₂O: reagent available from KatayamaChemical Industries Ltd.) as a metallic phosphate and anatase-typetitanium dioxide (TiO₂: reagent available from Wako Pure ChemicalIndustries, Ltd.) as an inorganic oxide were well mixed in a mortar, anda moisture thereof was adjusted with water. A ratio of phosphorus toiron in iron phosphate was 1/1. An amount of the titanium dioxide addedwas set so that titania accounted for 30 wt % in resultant titania-addediron phosphate.

Subsequently, a mixture obtained was molded using a so-called latchforming plate, and was dried in air at 120° C. A resultant cylindricalpellet with a diameter of 5 mm and a length of 6 mm was sintered in airat 500° C. for 3 hours. In this way, titania-added iron phosphate ascatalyst (b) was prepared. Then, a predetermined amount of titania-addediron phosphate was placed in the reactor for the secondary reaction(hereinafter referred to as secondary reactor).

Reaction conditions of the primary reaction were set identical to thosein the case of Example 2. Methanol was used as alcohol (b). Theproportions of GLO, oxygen, and methanol in the supply gas (b) preparedin the vaporizer connected to the secondary reactor and to be suppliedto the secondary reactor were set to, in this order, 3.0 vol %, 4.0 vol%, and 15.0 vol %, respectively (nitrogen gas balance). Incidentally,regarding oxygen and methanol, in order that the supply gas (b) with theforegoing composition was obtained, oxygen and methanol contained in thereactant gas resultant from the primary reaction were quantified, andthe same were supplied to the vaporizer for shortages only, through agas supply inlet of the secondary reactor.

The supply gas (b) of the foregoing composition was continuouslysupplied to the secondary reactor at a space velocity (SV) of 1,300hr⁻¹, so that the secondary reaction took place. A reaction temperaturewas set to 250° C.

A composition of the reactant gas obtained was analyzed in theaforementioned manner. Consequently, the conversion of GLO was 100%, theselectivity of MGO was 78%, and the yield of MGO with respect to EG was71%. Main reaction conditions and the result of the reaction are shownin Table 4.

EXAMPLE 18

The secondary reaction was made to take place under the same conditionsas those in Example 17 except that the reaction conditions in Example 11were adopted as reaction conditions of the primary reaction. Morespecifically, the secondary reaction was made to take place atrespective molar ratios of oxygen and methanol to GLO produced throughthe primary reaction that were made to agree with the molar ratioscalculated from the ratios in Example 17 (oxygen/GLO=1.3methanol/GLO=5.0). Consequently, the conversion of GLO was 100%, theselectivity of MGO was 78%, and the yield of MGO with respect to EG was69%. Main reaction conditions and the result of the reaction are shownin Table 4.

EXAMPLE 19

MGO was obtained from GLO that was obtained from EG, through the primaryand secondary reactions that were successively executed, with use ofalcohol (a) and alcohol (b) which were the same compound, while gasresultant from separation of produced matters from the reactant gasobtained through the secondary reaction (hereinafter referred to asrecycled gas) was re-used as a part of the supply gas (a) used in theprimary reaction. Incidentally, FIG. 1 is a block diagram schematicallyillustrating a device for and a process of reaction in the presentexample.

To be more specific, an SUS (Stainless Steel) pipe with an innerdiameter of 1 inch was used as a primary-reaction-use reaction pipe(primary reactor), in which placed was 88 g of metallic silver(electrolytic silver with a particle diameter of 20 to 30 mesh,available from Yokohama Metal Co., Ltd.) as catalyst (a). Further, on agas inlet side of the reaction pipe, a preheater for heating the supplygas (a) to be supplied to the reaction pipe to a predeterminedtemperature was attached. To the preheater, a vaporizer for vaporizingEG to be supplied to the preheater was attached. Further, the reactionpipe has an insulating material wound therearound for heat retention, sothat the temperature of a catalyst layer during the primary reaction(reaction temperature) would be kept at a predetermined temperature. Inother words, heat retention was ensured so that the primary reactionproceeded under conditions substantially equivalent to those ofadiabatic reaction.

The supply gas (a) is a mixture gas of a recycled gas (containingmethanol), vaporized EG, and air. The reaction conditions in Example 4were adopted as reaction conditions of the primary reaction. Therefore,the proportions of EG, oxygen, methanol as alcohol (a), and water in thesupply gas (a) were set to, in this order, 4.0 vol %, 4.8 vol %, 3.0 vol%, and 1.0 vol %, respectively (nitrogen gas balance). In other words,in order that the supply gas (a) with the foregoing composition wasconstantly obtained, oxygen, methanol, and the like contained in therecycled gas were quantified, and air was supplied thereto for oxygenshortage only. Triethyl phosphite was preliminarily added to EG suppliedto the foregoing vaporizer so that a ratio of phosphorus to EG became 60ppm.

On the other hand, a predetermined amount of titania-added ironphosphate as prepared in Example 17 as catalyst (b) was placed in thesecondary reactor. Further, a condenser for condensing the resultantreactant gas was attached on a gas outlet side of the secondary reactor,so that produced matters including MGO were separated in a form ofcondensed liquid from the reactant gas. A temperature of the recycledgas was adjusted so as to become 15° C. at the outlet of the condenser.A part of the recycled gas was purged, and the rest was continuouslysupplied to the primary-reaction-use reaction pipe. Incidentally, theconcentration of unreacted methanol contained in the recycled gas wasadjusted by control of a temperature of cooling medium used in thecondenser.

Methanol was used as alcohol (b). Proportions of GLO, oxygen, andmethanol in the supply gas (b) were set to, in this order, 2.8 vol %,3.7 vol %, and 14.0 vol %, respectively (nitrogen gas balance).Incidentally, regarding oxygen (air) and methanol, oxygen and methanolcontained in the reactant gas obtained through the primary reaction werequantified and the same were supplied to a vaporizing chamber forshortages only, so that the supply gas (b) with the foregoingcomposition could be obtained. The vaporizing chamber was attached on agas inlet side of the secondary reactor so that methanol was vaporized,while a mixture gas containing the reactant gas resultant from theprimary reaction, vaporized methanol, and air was formed andcontinuously supplied to the secondary reactor.

The supply gas (a) of the foregoing composition was continuouslysupplied to the reaction pipe at a space velocity (SV) of 45,000 hr⁻¹ sothat the primary reaction took place, while the supply gas (b) of theforegoing composition was continuously supplied to the secondary reactorat a space velocity of 1,300 hr⁻¹ so that the secondary reaction tookplace. The reaction temperature of the secondary reaction was set to250° C.

As a result of analysis of the composition of the reactant gas resultantfrom the primary reaction in the aforementioned manner, the conversionof EG was 100%, and the yield of GLO was 88%. On the other hand, thecomposition of the reactant gas resultant from the secondary reactionwas analyzed in the aforementioned manner. As a result, the conversionof GLO was 100%, the selectivity of MGO was 78%, and the yield of MGOwith respect to EG was 69%. Main reaction conditions and the result ofthe reaction are shown in Table 4.

EXAMPLE 20

The secondary reaction was made to take place under the same conditionsas those in Example 19 except that the reaction conditions in Example 5were adopted as reaction conditions of the primary reaction. Therefore,the primary and secondary reactions were successively executed.

The proportions of EG, oxygen, methanol, and water in the supply gas (a)were set to, in this order, 4.0 vol %, 4.8 vol %, 1.0 vol %, and 0 vol%, respectively (nitrogen gas balance). The proportions of GLO, oxygen,and methanol in the supply gas (b) were set to, in this order, 2.6 vol%, 3.6 vol %, and 13.0 vol %, respectively (nitrogen gas balance). Thetemperature of the recycled gas in the secondary reaction was set to 0°C. so that the concentration of unreacted methanol contained in therecycled gas was adjusted as above.

As a result of analysis of the composition of the reactant gas resultantfrom the primary reaction in the aforementioned manner, the conversionof EG was 100%, and the yield of GLO was 82%. On the other hand, thecomposition of the reactant gas resultant from the secondary reactionwas analyzed in the aforementioned manner. As a result, the conversionof GLO was 100%, the selectivity of MGO was 78%, and the yield of MGOwith respect to EG was 64%. Main reaction conditions and the result ofthe reaction are shown in Table 4.

Comparative Example 3

The secondary reaction was made to take place under the same conditionsas those in Example 19 except that the reaction conditions inComparative Example 1 were adopted as reaction conditions of the primaryreaction.

Therefore, the primary and secondary reactions were successivelyexecuted. The recycled gas, however, was not put in use.

The proportions of EG, oxygen, methanol, and water in the comparison-usesupply gas (a) were set to, in this order, 4.0 vol %, 4.8 vol %, 0 vol%, and 0 vol %, respectively (nitrogen gas balance). The proportions ofGLO, oxygen, and methanol in the comparison-use supply gas (b) were setto, in this order, 2.2 vol %, 3.0 vol %, and 11.0 vol %, respectively(nitrogen gas balance).

As a result of analysis of the composition of the reactant gas resultantfrom the primary reaction in the aforementioned manner, the conversionof EG was 100%, and the yield of GLO was 76%. On the other hand, thecomposition of the reactant gas resultant from the secondary reactionwas analized in the aforementioned manner. As a result, the conversionof GLO was 100%, and the selectivity of MGO was 77%, but the yield ofMGO with respect to EG was as low as 59%. Main reaction conditions andthe result of the reaction are shown in Table 4.

TABLE 4 COMPOSITION OF PRIMARY REACTION SUPPLY GAS (b) SPACE YIELD YIELD(vol %, NITROGEN VELOCITY REACTION CONVERSION SELECTIVITY OF EXAMPLE OFGLO GAS BALANCE) SV TEMPERATURE OF GLO OF MGO MGO (NO.) (%) GLO O₂ MeOH(hr⁻¹) (° C.) (%) (%) (%) EX. 17 2 89 3.0 4.0 15.0 1300 250 100 78 69EX. 18 11  91 3.2 4.3 16.0 1300 250 100 78 71 EX. 19 4 88 2.8 3.7 14.01300 250 100 78 69 EX. 20 5 82 2.6 3.6 13.0 1300 250 100 78 64 COMP. EX.3 COMP. 76 2.2 3.0 11.0 1300 250 100 77 59 EX. 1

Incidentally, the concrete embodiment and examples thus described in the“Best Mode for Carrying Out the Invention” are only intended to make thetechnical contents of the present invention explicit, and it will beobvious that the present invention may be varied in many ways. Suchvariations are not to be regarded as a departure from the spirit andscope of the invention, and all such modifications as would be obviousto one skilled in the art are intended to be included within the scopeof the following claims.

INDUSTRIAL APPLICABILITY

By the method of production of α-oxoaldehyde in accordance with thepresent invention, α-oxoaldehyde can be produced at a higher yield thanconventionally. Further, while the conventional method requires, forexample, supply (together with other materials) of massive water toobtain α-oxoaldehyde, the aforementioned method does not require supplyof water or the like for obtaining the α-oxoaldehyde because ofstabilization of α-oxoaldehyde by the presence of alcohol (a).Therefore, the aforementioned method has the following effect:α-oxoaldehyde can be produced at a higher yield than conventionally, andbesides, an oxoaldehyde solution or gas at a higher concentration thanconventionally can be stably obtained.

Thus, by the method of production of α-oxoaldehyde in accordance withthe present invention, the following effect can be achieved:α-oxoaldehyde can be produced at a further higher yield.

By the method of production of α-oxocarboxylate in accordance with thepresent invention, inconveniences involved in the conventional methods,for example, hydrolysis of α-oxocarboxylate due to the presence of waterin a reaction system, can be obviated. Therefore, the following effectcan be achieved: α-oxocarboxylate can be produced at a higher yield thanconventionally.

According to the method of production of α-oxocarboxylate in accordancewith the present invention, alcohol (a) need not be removed fromα-oxoaldehyde prior to production of α-oxocarboxylate. Therefore, thefollowing effect can be achieved: α-oxocarboxylate can be produced moreeasily.

According to the method of production of α-oxocarboxylate in accordancewith the present invention, reactant gas resultant from vapor phaseoxidation of α-oxoaldehyde and alcohol (b), gas resultant fromseparation of produced matters such as α-oxocarboxylate from theforegoing reactant gas, or gas containing alcohol uncollected uponseparation and collection of alcohol from the foregoing gas, can bere-used as a part, or preferably an entirety, of gas used for vaporphase oxidation of alkylene glycol (gas containing alkylene glycol andalcohol (a)). In this case, since the alcohol (a) re-used containsunreacted alcohol (b), the following effect can be achieved in the casewhere the same compound is used as the alcohol (a) and the alcohol (b)and the above-described re-usage is executed: α-oxocarboxylate can bemore easily and efficiently produced from alkylene glycol.

What is claimed is:
 1. A method of production of α-oxoaldehyde,comprising the step of oxidizing alkylene glycol in a vapor phase in thepresence of alcohol (a), oxygen and a catalyst (a), wherein alcohol (a)is not an alkylene glycol.
 2. The method of production of α-oxoaldehydeas set forth in claim 1, wherein a molar ratio of the alkylene glycol tothe alcohol (a) is in a range of 1/100 to 5/1.
 3. The method ofproduction of α-oxoaldehyde as set forth in claim 1, wherein proportionsof the alkylene glycol, the oxygen, and the alcohol (a) are, in thisorder, 1 percent by volume to 10 percent by volume, 1 percent by volumeto 10 percent by volume, and 0.01 percent by volume to 30 percent byvolume, respectively.
 4. The method of production of α-oxoaldehyde asset forth in claim 1, wherein the alkylene glycol is 1,2-diol.
 5. Themethod of production of α-oxoaldehyde as set forth in claim 1, whereinthe catalyst (a) is metallic silver, and/or metallic silver modifiedwith use of a phosphorus-containing compound.
 6. A method of productionof α-oxocarboxylate, comprising the steps of: oxidizing the alkyleneglycol in a vapor phase in the presence of alcohol (a), oxygen and acatalyst (a), wherein alcohol (a) is not an alkylene glycol so as toobtain α-oxoaldehyde; and oxidizing the α-oxoaldehyde, and alcohol (b)or olefin, in a vapor phase in the presence of oxygen and a catalyst(b).
 7. The method of production of α-oxocarboxylate as set forth inclaim 6, wherein one same compound is used as the alcohol (a) and thealcohol (b).
 8. The method of production of α-oxocarboxylate as setforth in claim 6, wherein the alcohol (a) contains unreacted alcohol (b)that is contained in a reactant gas resultant from the vapor phaseoxidation of the α-oxoaldehyde and the alcohol (b).
 9. The method ofproduction of α-oxocarboxylate as set forth in claim 6 wherein thecatalyst (a) is a metallic catalyst and/or an oxide catalyst, and thecatalyst (b) is a catalyst containing a phosphorus-containing inorganicoxide.
 10. The method of production of α-oxoaldehyde as set forth inclaim 1, wherein the catalyst (a) is a metallic catalyst and/or an oxidecatalyst.